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Overview The NFIQ2::Timer class provides a simple interface for measuring the execution time of operations. It’s used internally by NFIQ 2 to track the computation speed of quality measure algorithms.
Class Definition namespace NFIQ2 { class Timer { public: void start (); double getElapsedTime (); double stop (); }; }
Methods start Starts the timer.
Calling start() resets any currently running timer, discarding previous timing data.
Example: NFIQ2 ::Timer timer; timer . start ();
getElapsedTime Obtains the elapsed time since start() was called, without stopping the timer.
Returns: Elapsed time in milliseconds.Example: timer . start (); // ... perform operations ... double elapsed = timer . getElapsedTime (); std ::cout << "Elapsed: " << elapsed << " ms" << std ::endl; // Timer is still running
stop Stops the timer and returns the elapsed time.
Returns: Elapsed time in milliseconds since start() was called.Example: timer . start (); // ... perform operations ... double totalTime = timer . stop (); std ::cout << "Total time: " << totalTime << " ms" << std ::endl;
Usage Examples Basic Timing #include <nfiq2.hpp> NFIQ2 ::Timer timer; timer . start (); // Compute quality score NFIQ2 ::Algorithm model; unsigned int score = model . computeUnifiedQualityScore (image); double computeTime = timer . stop (); std ::cout << "Quality score " << score << " computed in " << computeTime << " ms" << std ::endl;
NFIQ2 ::Timer timer; timer . start (); // Stage 1 processStep1 (); double stage1Time = timer . getElapsedTime (); std ::cout << "Stage 1: " << stage1Time << " ms" << std ::endl; // Stage 2 processStep2 (); double stage2Time = timer . getElapsedTime () - stage1Time; std ::cout << "Stage 2: " << stage2Time << " ms" << std ::endl; // Total double totalTime = timer . stop (); std ::cout << "Total: " << totalTime << " ms" << std ::endl;
Timing Multiple Operations NFIQ2 ::Timer timer; std ::vector < double > timings; for ( const auto & image : images) { timer . start (); unsigned int score = model . computeUnifiedQualityScore (image); timings . push_back ( timer . stop ()); } // Calculate statistics double avgTime = std :: accumulate ( timings . begin (), timings . end (), 0.0 ) / timings . size (); std ::cout << "Average time per image: " << avgTime << " ms" << std ::endl;
Internal Usage The Timer class is used internally by quality measure algorithms to track computation speeds. You can access these timings through the QualityMeasures API:
auto algorithms = NFIQ2 :: QualityMeasures :: computeNativeQualityMeasureAlgorithms (image); // Get algorithm speeds in milliseconds auto speeds = NFIQ2 :: QualityMeasures :: getNativeQualityMeasureAlgorithmSpeeds (algorithms); for ( const auto & [algorithmID, speedMs] : speeds) { std ::cout << algorithmID << ": " << speedMs << " ms" << std ::endl; }
The Timer uses std::chrono::steady_clock for monotonic time measurement, ensuring accurate results even if the system clock is adjusted.
Resolution : Microsecond precision on most platformsOverhead : Minimal (typically < 1 microsecond)Thread Safety : Each Timer instance should be used by a single thread
See Also
Quality Measure Algorithms View algorithm computation speeds
Performance Guide Optimize quality measure computation
